The present invention relates to an automatic aiming adjustment apparatus for automatically adjusting an aiming direction of headlights installed on an automotive vehicle.
Conventionally, an aiming adjustment of headlights of an automotive vehicle has been carefully performed. If the optical axis of the headlights is directed toward a too much higher level due to an inclination of a vehicle body, the headlights may dazzle an oncoming vehicle's driver. If the optical axis of the headlights is directed toward a too much lower level, the subjective vehicle's driver may lose the far field of view. Thus, there is an earnest desire to accurately maintain the optical axis of the headlights within an optimum range.
Unexamined Japanese Patent Application No. 8-225039, published in 1986, discloses a related technique. According to this prior art, a vertical acceleration or deceleration is obtained from rotational speed signals of a vehicle wheel. The obtained vertical acceleration or deceleration is then used to obtain a signal representing a dynamic change of the level or height of the vehicle body. An actuator (i.e., operating element) is driven in accordance with the signal representing the dynamic change of the vehicle's level or height, to realize an automatic aiming adjustment for the headlights.
The above-described aiming adjustment for the vehicle headlights disclosed in the Unexamined Japanese Patent Application No. 8-225039 is simple in arrangement. However, this system is disadvantageous in that the aiming adjustment may be performed contrarily to the driver's intent. For example, when the vehicle is accelerated or decelerated on a rough road, the actuator is driven frequently in response to the surface roughness of the load.
Unexamined Japanese Utility Model Application No. 5-29857, published in 1993, discloses another related technique. According to this prior art, a vehicle's stopping condition is detected. And, the aiming adjustment of the headlights is performed based on a variation in the vehicle height when the automotive vehicle is stopped.